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Subject: Re: [Qemu-devel] [PATCH 59/60] AArch64: Add "Floating-point
	data-processing (3
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To: Alexander Graf <agraf@suse.de>
Cc: Peter Maydell <peter.maydell@linaro.org>, Michael Matz <matz@suse.de>, qemu-devel@nongnu.org, C Fontana <claudio.fontana@linaro.org>, Dirk Mueller <dmueller@suse.de>, Laurent Desnogues <laurent.desnogues@gmail.com>, Christoffer Dall <christoffer.dall@linaro.org>

On 09/26/2013 05:48 PM, Alexander Graf wrote:
> +    if (is_neg) {
> +        gen_helper_vfp_negs(tcg_op1, tcg_op1);
> +        gen_helper_vfp_negs(tcg_op3, tcg_op3);
> +    }
> +
> +    gen_helper_vfp_muls(tcg_res, tcg_op1, tcg_op2, fpst);
> +    if (is_sub) {
> +        gen_helper_vfp_subs(tcg_res, tcg_op3, tcg_res, fpst);
> +    } else {
> +        gen_helper_vfp_adds(tcg_res, tcg_op3, tcg_res, fpst);
> +    }
> +

Unlike original vfp, aarch64 requires infinite precision intermediate.
Which means that you need to use float_muladd.  Note that

  opa_neg = float_muladd_negate_c
  op1_neg = float_muladd_negate_product

Or those together into the 4th argument to float_muladd.


r~